In a conventional motor vehicle, the internal combustion engine of the vehicle is “started” by an ignition system that includes an electrical starter motor, a battery power source, and a key-operated ignition switch. When the ignition switch is closed, current is supplied by the battery power source to the starter motor, which in turn, “starts” the internal combustion engine.
Security of the ignition system is dependent upon the integrity of the key-operated ignition switch. By shorting the ignition switch, the ignition system circuitry can be closed without the need of a key to close the ignition switch. This is known as “hot wiring” starting. Shorting the ignition switch is frequently the method used to start the internal combustion engine during theft of a motor vehicle. The switch is typically located on the steering column of the vehicle which is surrounded by a circular metal housing. By breaking open the metal housing, the switch may thereafter be quickly and easily shorted. Alternatively, the key switch may be broken by the forceful insertion of an object such as a screwdriver into the keyhole and the screwdriver thereafter effectively acts as a key to close the switch.
Several systems have been developed which attempt to make theft of the vehicle more difficult. Such systems include vehicle alarms that sound a siren or horn when a vehicle is broken into and/or prevent the vehicle from starting. Other systems are mechanical devices that secure to the steering column and/or the gas pedal to prevent their operation even when the car is hot wired. Unfortunately, audible alarms and mechanical devices require activation or installation by the driver. As such, they are often forgotten by the vehicle owner, and not enabled. In addition, audible alarms have become so commonplace that they are frequently ignored. Thus, these prior art audible alarms and mechanical devices are ineffective for satisfactorily protecting vehicles against theft.
Another system, known as a transponder-based immobilizer system, includes a contactless data carrier (transponder) embedded in the vehicle key. The transponder is powered by a radio frequency field generated by a radio frequency identification (RFID) reader in the vehicle. The transponder sends an authorization code to the RFID reader, which signals engine management electronics to immobilize the car if it does not find or does not accept the transmitted authorization code. The transponder-based immobilizer system is advantageous over prior art driver-activated alarms and mechanical devices because it requires no intervention by the driver in order to activate the immobilizer system.
While an immobilizer system can prevent theft of a vehicle by merely shorting the ignition key switch, such a system suffers from several disadvantages. For example, since the transponder is embedded on the key, the vehicle owner cannot readily have a duplicate key made. Rather, the vehicle owner is required to obtain duplicate keys through the vehicle dealer or through an authorized provider, which is inconvenient for the vehicle owner and significantly more expensive than merely having a duplicate key made at a local hardware store.
In addition, if the key with the embedded transponder is stolen, the thief can still start the car. Such situations arise in a home robbery where the thief finds the vehicle keys setting in the home or in a car jacking in which the thief takes the key from the driver.
Yet another problem arises with the prior art transponder-based immobilizer systems in that these systems are only provided in new vehicles by the original equipment manufacturer. As such, individuals having older model vehicles, collectable vehicles, a fleet of vehicles, and such, cannot employ this technology to protect their vehicles.